Due to manufacturing variability the size of the drops in inkjet printers is variable within a manufacturing tolerance. Typically this tolerance may be on the order of 15% for thermal inkjet printheads. This variability in drop size directly affects the amount of ink that is delivered by the printhead. This variability may be called the drop weight variability of the printhead.
For consumer home printers usually no attempt has been made to calibrate the drop weight of a printhead, in part because for home printers a typical tri-color printhead outputs cyan/magenta/yellow. Thus if the drop weight for a printhead is heavier or lighter than the nominal printhead, the customer will not see a color hue shift because all three colors are equally effected. Also since this single printhead is scanned across the page the color content across the page will appear consistent. For a printing platform employing a page wide array of dies, this may not be true. For example, assume an array includes ten dies spatially arrange to provide a page wide configuration. An example is to print a solid patch of cyan across the page. Since ten separate dies are involved, each with its own drop weight characteristic, the apparent intensity of this cyan patch will vary across the page, as a function of the die drop weights, and the human eye may readily be able to discern the die boundaries.